Modulation of the photocatalytic performance of g-C3N4 by two-sites co-doping using variable valence metal

• Published in: Applied surface science 2020-01, Vol.500, p.144036, Article 144036
• Main Authors: Dai, Yanhui, Gu, Yingjie, Bu, Yuyu
• Format: Article
• Language: English
• Subjects: Bridged bond structure; Carbon nitride; Copper; Double-site doping; Mineralization
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2019.144036

Variable valence metal Cu with univalent and divalent conversion capacity was developed to achieve the interlayer doping and intralayer co-doping of g-C3N4. Univalent Cu atom prefer to dope into the interlayer of g-C3N4 to form a steady bridged bond structure to improve the charge transfer capacity of g-C3N4. Divalent Cu atoms can be doped on the intralayer of g-C3N4, to form an unstable but active-catalysis site. [Display omitted] •g-C3N4 co-doped by Cu (I) and Cu (II).•Interlayer doping of g-C3N4 by univalent Cu atom sites.•Intralayer doping by divalent Cu atom sites.•Photocatalytic mineralize antibiotic to CO2 and H2O completely by visible light. Copper element was employed to achieve the interlayer doping and intralayer doping in g-C3N4 (CN). Univalent Cu single atom prefer to dope into the interlayer site of CN to form a steady bridged bond structure. Further increasing the doping amount of Cu, except for the univalent Cu at the interlayer, some divalent Cu single atoms can be doped on the intralayer site of CN to form an unstable but active-catalysis structure. Electrochemical and theoretical calculation results reveal that Cu-interlayer doping can form an energy gradient between the different CN layers to decrease the charge transfer energy barrier between them. More importantly, these interlayer photogenerated electrons will converge on the divalent Cu, a catalysis active site for the photogenerated electrons, inducing more superoxide radicals and high activity. This two-sites modified CN, can mineralize a refractory antibiotic Norfloxacin (NOR) to CO2 and H2O completely under visible light stimulation, and the two-sites co-doping method provides a reference for CN photocatalyst modification to solve the questions of insufficient redox energy and low photons quantum efficiency of CN.